In a container manufacturing plant, container ends are commonly formed separately from the container body and then attached, e.g., by curling, to the container body. In the manufacture of container ends, a number of processing steps may be performed. For example, the end may be stamped from sheet material, a rim protruding from a top surface of the end may be formed about a circumference of the end, a gutter may be formed on the top surface adjacent the rim, an opening assembly may be installed on the end, the end may be cleaned and coated, and informational symbols may be printed onto or stamped into the end. The ends may therefore be transported to a number of processing stations to carry out such operations before being attached to the container body.
The ends are typically transported between processing stations in a longitudinal stick, i.e., a column of circumferentially aligned ends. The stick is easily maintained where the ends are rimmed, or where an indentation or cavity is otherwise provided in a surface of each end, thereby allowing adjacent ends to be nested. As used herein, the term "nested" refers to adjacent ends having a region of longitudinal overlap and the term "nestable" refers to ends shaped such that they are capable of being nested. By arranging the ends into a nested stick, the ends can be transported compactly and provided to machinery in an organized fashion thereby reducing the likelihood of mishandling by the machinery.
One problem encountered in container manufacturing plants is inverted ends, i.e., where the top or bottom surface of an end abuts against the top or bottom surface, respectively, of an adjacent end rather than nesting. Inverted ends may result in mishandling by machinery and necessitate machinery shut-down. To reduce such mishandling and shut-down, some plants utilize operators to identify and remove inverted container ends before they enter machinery. However, this increases plant labor requirements and machinery may still be shut-down occasionally to permit inverted end removal. Thus, manually removing container ends results in reduced plant efficiency and output.
One apparatus for automated removal of inverted rimmed ends includes an arm which hooks onto the rims and pulls the inverted ends from the stick. For example, such an arm may be resiliently disposed against the stick so that the arm enters a gap in the stick due to a non-nested, inverted end. As the stick moves, the arm hooks onto the rim of the advancing inverted end and pulls it from the stick. However, such an apparatus is inapplicable to sticks wherein inverted ends are oriented such that the rim is at the leading edge of the inverted end. Rather, such apparatus are only useful in connection with sticks wherein inverted ends are oriented such that the rim is at the trailing edge of an inverted end so that the arm can hook onto the rim. Further, such an apparatus requires a movable member which may require maintenance or be subject to failure.
Another apparatus for automated removal of inverted ends comprises a sensing mechanism, such as an optical sensor, and a movable member to eject inverted ends from the stick. For example, a piston may be moved against particular inverted ends identified by the sensing mechanism, thereby moving the inverted ends relative to adjacent ends and ejecting the inverted ends from the stick. However, such an apparatus requires a moving piston which may malfunction or require servicing. In addition, the need for a mechanism to sense or identify inverted ends complicates apparatus design and implementation.
Therefore there is a need for a method and apparatus for removing inverted container ends from a stick which is applicable to both forward and rearward moving inverted ends. There is also a need for such a method and apparatus which does not require a moving part such as a piston to eject the inverted end. Preferably such a method and apparatus would be easily adaptable for use with existing plant equipment and would be less complicated than the methods/apparatus described above.